The Tranquil Princept is a historical Princept who encountered the True Divine.
According to Gur Sevraq, the Tranquil Princept "saw the might of God" when Logos Kantel arrived on Partizan (moon). Rather than embrace the miraculous "potency of progression" which God offered, the Princept made a vow to enact generational change[1]. In return, God decreed that the oath would be broken if the Principality entered the Scutum–Centaurus Arm before progressing beyond their imperialistic impulses.
In order to achieve their vow and keep the True Divine out of the public eye, the Tranquil Princept founded the Curtain of Divinity, which would eventually be more interested in controlling the state than improving or dismantling it.